The advent of global communications networks such as the Internet has presented commercial opportunities for reaching vast numbers of potential customers. Electronic messaging, and particularly electronic mail (“e-mail”), is becoming increasingly pervasive as a means for disseminating unwanted advertisements and promotions (also denoted as “spam”) to network users.
The Radicati Group, Inc., a consulting and market research firm, estimates that as of August 2002, two billion junk e-mail messages are sent each day—this number is expected to triple every two years. Individuals and entities (e.g., businesses, government agencies) are becoming increasingly inconvenienced and oftentimes offended by junk messages. As such, junk e-mail is now or soon will become a major threat to trustworthy computing.
A key technique utilized to thwart junk e-mail or spam is employment of filtering systems and/or methodologies. However, spammers are continually changing their techniques in order to avoid filters. It is thus desirable to update filters quickly and automatically as spammer techniques change and to propagate them to end applications operated by messaging clients and/or servers.
For example, there can be approximately 100 million copies of messaging programs in use by clients. In addition, new spam filters can be created everyday. Because the spam filters can be rather large and distribution of them to each client operating a copy of the filter could be required everyday, such a practice can be problematic if not prohibitory on both the client and filter-provider sides. In particular, clients may be required to constantly download large files, hence consuming significant amounts of processor memory and decreasing processing speeds. Because the filter provider may have to update all copies of the filter for all users and/or clients everyday, an enormous and impracticable amount of bandwidth and servers may be required. Providing new filters more frequently than once a day can be nearly, if not completely, impossible under such conditions.